Some handicapped persons have muscular contraction problems that make them contract their legs together (this movement is known as abduction) and hit their knees. Such contraction can hurt them involuntarily and to prevent this, there are different abduction abutment supports. The support places the abutment between the legs of the person and prevents the knees from hitting each other. Some known abutment supports are fixed to the seat, such as the one described in Wilkie et al. U.S. Pat. No. 5,636,900, and may not pivot downwardly in order to be moved out of the way of the person when it is necessary.
Other known abutment supports may pivot downwardly to clear the way of the person sitting on the wheelchair so he or she can move out or move on the wheelchair easily. These pivotable abutment supports are provided with a locking mechanism that locks the abutment between the legs of the person and can be unlocked in order to move the abutment out of the way when desired.
The locking means of one known pivotable abutment support comprises a protuberance on one side of a lower end of a rod and two plates sandwiching the lower end of the rod. One plate has a recessed area adapted to receive the protuberance. An abutment is mounted on an upper end of the rod. When the rod is extended upwardly and the abutment lies above the seat, the protuberance fits into the recessed area and maintains the rod in the upstanding position, i.e. between the legs of the person. To unlock the rod, one has to press behind the abutment and pivot the rod downwardly so that the protuberance disengages the recessed area. One of the disadvantages of this locking means is that the protuberance is subject to wear and tear rapidly and consequently loses its effectiveness very rapidly.
The pivotable abutment support described in Kornberg U.S. Pat. No. 5,320,416 has a different locking mechanism to keep the rod between the legs (or knees) of the person. Its locking mechanism comprises a rail system designed to longitudinally forwardly and rearwardly adjust the abutment location, a sliding member fixed to a rod on which an abutment is mounted and adapted to slide in the rail system. At a forward limit position of the rail system, the sliding member disengages the rail and may freely pivot downwardly together with the rod and the abutment that are fastened to the sliding member. To keep the rod upwardly extending, the sliding member has to be pushed rearwardly in order to engage the rail. Then, the sliding member is secured in a longitudinal desired position on the rail system by a locking pin engaging it.
The pivotable abutment support described in Suhre U.S. Pat. No. 4,617,919 uses another locking means which comprises a release pin allowing the rod to pivot downwardly.
There is a need for a locking means for a pivotable abduction abutment support that does not wear and tear easily, and is simple to manipulate. Advantageously, the locking means is unlocked by using only one hand, and is locked automatically when the rod is pivoted back into the upstanding position.